WO2014157202A1

WO2014157202A1 - Dehydrogenation catalyst for naphthenic hydrocarbons, method for producing dehydrogenation catalyst for naphthenic hydrocarbons, system for producing hydrogen, and method for producing hydrogen

Info

Publication number: WO2014157202A1
Application number: PCT/JP2014/058281
Authority: WO
Inventors: 倫視中泉; 智史古田
Original assignee: Ｊｘ日鉱日石エネルギー株式会社
Priority date: 2013-03-28
Filing date: 2014-03-25
Publication date: 2014-10-02
Also published as: CN105102120A; JPWO2014157202A1; EP2979756A1; US20160045899A1; EP2979756A4; JP6297538B2

Abstract

Provided is a dehydrogenation catalyst for naphthenic hydrocarbons, which has excellent dehydrogenation activity. One embodiment of the dehydrogenation catalyst for naphthenic hydrocarbons according to the present invention is provided with: a carrier that contains aluminum oxide; platinum; and a group 3 metal.

Description

Dehydrogenation catalyst for naphthenic hydrocarbons, method for producing dehydrogenation catalyst for naphthenic hydrocarbons, system for producing hydrogen, and method for producing hydrogen

The present invention relates to a dehydrogenation catalyst for naphthenic hydrocarbons, a method for producing the dehydrogenation catalyst, a hydrogen production system using the dehydrogenation catalyst, and a method for producing hydrogen.

In recent years, it is expected that a fuel cell using hydrogen with a low environmental load as a fuel will be used as a power source for automobiles and the like. Naphthenic hydrocarbons (cyclic hydrocarbons) are used in the process of transporting, storing and supplying hydrogen. For example, in a hydrogen production facility, naphthenic hydrocarbons are generated by hydrogenation of aromatic hydrocarbons. This naphthenic hydrocarbon is transported to a hydrogen consumption area or stored in the consumption area. In the consumption area, hydrogen and aromatic hydrocarbons are generated by dehydrogenation of naphthenic hydrocarbons. This hydrogen is supplied to the fuel cell. Naphthenic hydrocarbons are liquid at room temperature, have a smaller volume than hydrogen gas, are less reactive than hydrogen gas, and are safe. Therefore, naphthenic hydrocarbons are more suitable for transportation and storage than hydrogen gas.

As a dehydrogenation catalyst for naphthenic hydrocarbons, a catalyst in which a platinum-rhenium bimetal is supported on an alumina carrier is known (see Non-Patent Document 1 below).

An object of the present invention is to provide a dehydrogenation catalyst for naphthenic hydrocarbons having excellent dehydrogenation activity, a method for producing the dehydrogenation catalyst, a system for producing hydrogen using the dehydrogenation catalyst, and a method for producing hydrogen. And

The dehydrogenation catalyst for naphthenic hydrocarbons according to one aspect of the present invention includes a support containing aluminum oxide, platinum, and a Group 3 metal.

In the dehydrogenation catalyst according to one aspect of the present invention, the supported amount of the Group 3 metal is 0.1 to 5.0% by mass with respect to the total mass of aluminum oxide in terms of Group 3 metal oxide. It may be.

In the dehydrogenation catalyst according to one aspect of the present invention, the supported amount of platinum is m _P mass% with respect to the total mass of aluminum oxide in terms of simple platinum, and the supported amount of the Group 3 metal is In terms of Group 3 metal oxide, m ₃ / m _P may be (10/3) to 4 when m ₃ mass% with respect to the total mass of aluminum oxide.

A method for producing a dehydrogenation catalyst for naphthenic hydrocarbons according to one aspect of the present invention includes a step of producing a carrier containing aluminum oxide and carrying a Group 3 metal, and carrying a platinum compound solution on the carrier. And firing the carrier.

In the method for producing a dehydrogenation catalyst according to one aspect of the present invention, the platinum compound may contain an amine or ammonia.

In the method for producing a dehydrogenation catalyst according to one aspect of the present invention, a pseudo-boehmite state aluminum hydroxide, a Group 3 metal nitrate aqueous solution, and nitric acid are kneaded to prepare a kneaded product. The carrier may be produced by producing pellets by extrusion molding and firing the pellets.

A hydrogen production system according to one aspect of the present invention includes a dehydrogenation reactor that includes the dehydrogenation catalyst and generates hydrogen by dehydrogenation of a naphthenic hydrocarbon using the dehydrogenation catalyst.

The hydrogen production method according to one aspect of the present invention includes a step of generating hydrogen by dehydrogenation of a naphthenic hydrocarbon using the dehydrogenation catalyst.

According to the present invention, there are provided a dehydrogenation catalyst for naphthenic hydrocarbons excellent in dehydrogenation activity, a method for producing the dehydrogenation catalyst, a hydrogen production system and a method for producing hydrogen using the dehydrogenation catalyst. Can do.

FIG. 1 is a diagram showing the relationship between the type of Group 3 metal contained in the dehydrogenation catalyst and the platinum surface area. FIG. 2 is a diagram showing the relationship between the elapsed time of the dehydrogenation reaction of methylcyclohexane (MCH) using a dehydrogenation catalyst containing scandium and the conversion rate of MCH. FIG. 3 is a graph showing the relationship between the elapsed time of the dehydrogenation reaction of methylcyclohexane (MCH) using a dehydrogenation catalyst containing cerium and the conversion rate of MCH. FIG. 4 is a graph showing the relationship between the amount of cerium supported in the dehydrogenation catalyst and the platinum surface area. FIG. 5 is a schematic view showing an embodiment of a hydrogen production system according to the present invention. FIG. 6 is a diagram showing the relationship between the amount of cerium oxide supported and the platinum surface area in the dehydrogenation catalyst according to the present invention. FIG. 7 is a graph showing the relationship between the supported amount of platinum, the degree of platinum dispersion, and the relative reaction rate of the dehydrogenation reaction in the dehydrogenation catalyst according to the present invention. FIG. 8 is a diagram showing the relationship between the molar ratio of the Group 3 metal and platinum in the dehydrogenation catalyst according to the present invention and the molar ratio of CO adsorbed on platinum.

Hereinafter, preferred embodiments of the present invention will be described. However, the present invention is not limited to the following embodiment.

(Dehydrogenation catalyst for naphthenic hydrocarbons)
The dehydrogenation catalyst for naphthenic hydrocarbons according to this embodiment includes a support containing aluminum oxide, platinum (Pt), and a Group 3 metal.

Platinum is supported on the carrier as a large number of atoms, clusters or fine particles. That is, platinum is present on the surface of aluminum oxide contained in the carrier. The surface is a portion where the active metal is substantially supported and the catalytic reaction proceeds, and the thickness thereof may be a single molecule or more of aluminum oxide. The particle size of the platinum fine particles supported on the carrier is not particularly limited, but may be, for example, 10 nm or less. The Group 3 metal is also supported on the support in the same manner as platinum. That is, the Group 3 metal is present on the surface of the aluminum oxide. Further, the Group 3 metal may be contained in the aluminum oxide. In other words, in the crystal structure of aluminum oxide, a part of aluminum (Al) may be replaced by a Group 3 metal, and a part of the carrier may be an oxide of a Group 3 metal (for example, cerium oxide).

In a reducing atmosphere, when a naphthenic hydrocarbon comes into contact with a dehydrogenation catalyst, platinum as an active site extracts at least a pair of hydrogen atoms from the naphthenic hydrocarbon, and a hydrogen molecule and an unsaturated hydrocarbon (for example, an aromatic hydrocarbon). Produces. The activity of the catalyst that promotes such a dehydrogenation reaction is called dehydrogenation activity.

The dehydrogenation activity is evaluated based on, for example, the conversion C (unit: mol%) of a naphthene hydrocarbon defined by the following formula (1). A high conversion C means that the dehydrogenation activity of the dehydrogenation catalyst is high.
Conversion C = (M2 / M1) × 100 = {M2 / (M2 + M3)} × 100 (1)
In Formula (1), M1 is the number of moles of naphthenic hydrocarbon supplied to the reaction vessel in which the dehydrogenation catalyst is arranged. M2 is the number of moles of aromatic hydrocarbons contained in the product of the dehydrogenation reaction. M3 is the number of moles of naphthenic hydrocarbon remaining after the dehydrogenation reaction. For example, when the conversion rate C is the conversion rate of methylcyclohexane, M1 and M3 are the number of moles of methylcyclohexane, and M2 is the number of moles of toluene.

In the present invention, when cerium is added to aluminum oxide, platinum acting as an active site on the catalyst surface increases or the function of platinum as an active site increases due to its physical, electronic or chemical action. The present inventors think that. In addition, the inventors consider that one of the more specific reasons for achieving the effect of the present invention is as follows. However, the specific reason why the effect of the present invention is achieved is not limited to the following.

In this embodiment, since the Group 3 metal adheres to the aluminum oxide or is contained inside the aluminum oxide, a part of oxygen constituting the oxide of the aluminum oxide or the Group 3 metal is reduced in the reducing atmosphere. In this case, a large number of lattice defects are formed on the carrier. The platinum is fixed to the carrier by fitting the platinum into the lattice defect. As a result, platinum is more highly dispersed by heating during the dehydrogenation reaction, and movement and aggregation of platinum on the support surface are suppressed. That is, in this embodiment, compared with a conventional dehydrogenation catalyst not containing a Group 3 metal, the platinum surface area during the dehydrogenation reaction is increased and the aggregation of platinum is suppressed, so that the dehydrogenation activity and durability are improved. improves. Such an effect is remarkable when the dehydrogenation catalyst contains cerium (Ce) as a Group 3 metal. Formation of lattice defects due to the Group 3 metal is confirmed, for example, by observing the chemical shift of the peak derived from the Group 3 metal constituting the oxide in the photoelectron spectroscopy (XPS) spectrum of the dehydrogenation catalyst. be able to.

Further, in this embodiment, since the aggregation of platinum during the dehydrogenation reaction is suppressed as compared with the dehydrogenation catalyst not containing a Group 3 metal, the deactivation over time associated with the dehydrogenation reaction is suppressed, and the reaction time is reduced. As time passes, the dehydrogenation activity tends to be maintained substantially constant. On the other hand, the dehydrogenation activity of a dehydrogenation catalyst that does not contain a Group 3 metal continues to decrease as the reaction time elapses. That is, in this embodiment, the catalyst life is improved as compared with a dehydrogenation catalyst not containing a Group 3 metal.

Furthermore, in this embodiment, since the dehydrogenation catalyst contains a Group 3 metal, its dehydrogenation activity is improved, so that the supported amount of platinum is the same as that of a conventional dehydrogenation catalyst not containing a Group 3 metal. However, it is possible to have a decatalytic activity superior to that of conventional dehydrogenation catalysts. In other words, the present embodiment has a decatalytic activity equivalent to that of a conventional dehydrogenation catalyst even when the amount of platinum supported is smaller than that of a conventional dehydrogenation catalyst not including a Group 3 metal. Is possible. Therefore, in the present embodiment, it is possible to reduce the amount of expensive platinum supported without sacrificing the dehydrogenation activity. The above-mentioned effect due to the Group 3 metal was confirmed for the first time by a combination of aluminum oxide and platinum.

Although the Group 3 metal increases the platinum surface area as described above, the Group 3 metal itself does not function as an active point of the dehydrogenation catalyst. Therefore, even if only the Group 3 metal among platinum and the Group 3 metal is supported on the carrier, the catalyst cannot have a high dehydrogenation activity.

Examples of the naphthene hydrocarbon (cyclic hydrocarbon) include one or more selected from the group consisting of cyclohexane, methylcyclohexane, dimethylcyclohexane, decalin, 1-methyldecalin, 2-methyldecalin and 2-ethyldecalin. Use it. These compounds are called organic hydrides.

The surface of the support may be composed of porous aluminum oxide. The carrier has any of the following functions.
Helps the main catalyst to increase its catalytic activity or selectivity.
Increase the dispersibility of the active metal.
Extend catalyst life.
Increase the mechanical strength of the catalyst structure.
Solidify the catalyst.
Enables catalyst molding.
A structure that substantially carries an active metal.

The type of aluminum oxide is not limited, but specific examples of aluminum oxide include α-alumina, δ-alumina, θ-alumina, γ-alumina, and alumite. The specific surface area of aluminum oxide is not particularly limited, but is approximately in the range of 100 to 500 m ² / g.

The shape of the carrier is not particularly limited. For example, the carrier may be in the form of pellets, a plate, or a honeycomb.

As the Group 3 metal, one or more selected from scandium (Sc), yttrium (Y), lanthanoid and actinoid may be used. Examples of the lanthanoid include lanthanum (La) and cerium (Ce). Of these Group 3 metals, cerium is most preferred. As described above, the dehydrogenation catalyst can have a remarkably high dehydrogenation activity by containing cerium.

The amount of platinum supported on the dehydrogenation catalyst is not particularly limited, but is 0.1 to 5.0% by mass or 0.2 to 1.0% by mass with respect to the total mass of aluminum oxide in terms of platinum alone. It may be. When the amount of platinum supported is not less than the above lower limit, the dehydrogenation activity is further improved. When the supported amount of platinum is equal to or more than the above upper limit value, the degree of improvement in the catalytic activity accompanying the increase in the supported amount of platinum becomes moderate. Moreover, since the price of platinum is very high, the amount of platinum supported is limited for practical use of the dehydrogenation catalyst. Note that the effect of the present invention can be achieved even when the supported amount of platinum is outside the above numerical range.

The amount of Group 3 metal supported in the dehydrogenation catalyst is not particularly limited, but may be 0.1 to 5.0% by mass with respect to the total mass of aluminum oxide in terms of Group 3 metal oxide. . When the amount of the Group 3 metal supported is not less than the above lower limit, the platinum surface area is further increased and the dehydrogenation activity is further improved. When the amount of the Group 3 metal supported is not more than the above upper limit value, it is easy to increase the platinum surface area while maintaining the mechanical strength of the dehydrogenation catalyst. Further, when the amount of the Group 3 metal supported is not more than the above upper limit value, the carrier can be easily molded in the production process. When the loading amount of the Group 3 metal greatly exceeds the above upper limit value, the performance of the support is lowered and the platinum surface area tends to decrease. However, the effect of the present invention can be achieved even when the loading amount of the Group 3 metal is out of the above numerical range. For example, the amount of the Group 3 metal supported in the dehydrogenation catalyst may be greater than 0% by mass and 20% by mass or less in terms of Group 3 metal oxide. The supported amount of the Group 3 metal in the dehydrogenation catalyst may be greater than 0% by mass and 10% by mass or less in terms of Group 3 metal oxide. The amount of Group 3 metal supported in the dehydrogenation catalyst may be 0.3 to 5.0% by mass or 2.0 to 3.0% by mass in terms of Group 3 metal oxide. When the amount of Group 3 metal supported is 2.0 to 3.0% by mass in terms of Group 3 metal oxide, the platinum surface area tends to increase particularly easily.

The supported amount of platinum is m _P mass% with respect to the total mass of aluminum oxide in terms of platinum alone, and the supported amount of group 3 metal is the total amount of aluminum oxide in terms of oxide of group 3 metal. When m ₃ mass% with respect to mass, m ₃ / m _P may be (10/3) to 4. In this case, the degree of platinum dispersion is high and the reaction rate of the dehydrogenation reaction tends to be high. M ₃ / m _P may be 2.78 to 3.64 because the platinum dispersity is high and the reaction rate of the dehydrogenation reaction tends to be high.

(Method for producing dehydrogenation catalyst)
The dehydrogenation catalyst according to the present embodiment is produced, for example, by a method including a Group 3 metal supporting step and a subsequent platinum supporting step as follows. In the group 3 metal supporting step, a carrier containing aluminum oxide and supporting the group 3 metal is prepared. In the platinum supporting step, a platinum compound solution is supported on a carrier and the carrier is fired.

[Group 3 metal loading process]
A solution (for example, an aqueous solution) of a Group 3 metal compound is supported on a support (for example, a porous aluminum oxide support). Examples of the supporting method include an incipient wetness method, a pore filling method, an adsorption method, an immersion method, an evaporation to dryness method, a spray method, an ion exchange method, a liquid phase reduction method, and the like. By these methods, a Group 3 metal salt is attached to the surface of the support. The amount of Group 3 metal supported in the dehydrogenation catalyst may be adjusted by the concentration or amount of the Group 3 metal compound.

As the Group 3 metal compound, for example, nitrate, sulfate, carbonate, acetate, phosphate, oxalate, borate, chloride, alkoxide, acetylacetonate, etc. may be used.

The group 3 metal is supported on the carrier by firing the carrier on which the salt of the group 3 metal is adhered and decomposing the salt. The firing temperature may be any temperature at which the thermal decomposition of the salt proceeds, for example, about 300 to 600 ° C.

In place of the above-described supporting step, there is also a method of forming a mixture having a porous structure by mixing a Group 3 metal compound with aluminum oxide or a precursor thereof before having a stable porous structure. Examples of such a method include a kneading method, a sol-gel method, and a coprecipitation method. Alternatively, aluminum oxide and Group 3 metal oxide may be physically mixed. The Group 3 metal may be added to the support by molding a mixture of the raw material powder of the support and the Group 3 metal compound and firing the molded body. As the carrier raw material powder, for example, boehmite, which is a raw material of γ-alumina, may be used. The firing temperature in this case may be a temperature at which the pyrolysis of the Group 3 metal compound proceeds and γ-alumina is produced by the boehmite sintering. Such a firing temperature is, for example, about 300 to 600 ° C.

By kneading aluminum hydroxide in a pseudo-boehmite state, an aqueous solution of a nitrate of Group 3 metal, and dilute nitric acid, preparing a kneaded material, producing pellets by extrusion molding of the kneaded material, and firing the pellets A carrier may be prepared. By producing the carrier by such a method, the Group 3 metal is easily dispersed in the carrier. In a dehydrogenation catalyst produced using such a carrier, the platinum surface area tends to be large, and high dehydration activity is likely to be obtained. The hydroxide of the pseudoboehmite state aluminum, for example, represented by the composition formula of AlOOH or _{_{_{Al 2 O 3 · H 2 O}}} . The kneaded product is also called a dough. The pH of the kneaded material may be adjusted to 3-7. By adjusting the pH, the kneaded product has an appropriate viscosity, and the kneaded product is easily molded. The pH of the kneaded product varies depending on the amount of nitric acid added. You may adjust pH of a kneaded material by adding ammonia water to a kneaded material.

[Platinum loading process]
A platinum compound solution (for example, an aqueous solution) is supported on a carrier on which a Group 3 metal is supported. Examples of the supporting method include an incipient wetness method, a pore filling method, an adsorption method, an immersion method, an evaporation to dryness method, a spray method, an ion exchange method, and a liquid phase reduction method. By these methods, the platinum compound is attached to the surface of the carrier. The amount of platinum supported in the dehydrogenation catalyst may be adjusted by the concentration or amount of the platinum compound.

The platinum compound is not particularly limited, but is required to be soluble in a liquid solvent. For example, tetrachloroplatinic acid, potassium tetrachloroplatinate, ammonium tetrachloroplatinate, sodium tetrachloroplatinate, bis (acetylacetonato) platinum, diamminedichloroplatinum, dinitrodiammine platinum, dinitrodiammine platinum nitrate, dinitrodiammine platinum ammonia Solution, ethanolamine platinum, tetraammine platinum dichloride, tetraammine platinum hydrochloride, tetraammine platinum nitrate, tetraammine platinum acetate, tetraammine platinum carbonate, tetraammine platinum phosphate, hexaammine platinum tetrachloride, hexaammine platinum hydrochloride, hexa Ammine platinum hydrochloride, bis (ethanolammonium) hexahydroxoplatinum (IV), sodium hexahydroxoplatinum (IV), hexahydroxoplatinum ( Potassium V) acid, platinum nitrate, may be used sulfuric platinum. The platinum compound preferably contains an amine or ammonia. In this case, the platinum surface area in the dehydrogenation catalyst tends to increase. The platinum compound containing amine or ammonia is dinitrodiammine platinum nitrate, which may be at least one selected from the group consisting of dinitrodiammine platinum nitrate, dinitrodiammine platinum ammonia solution, ethanolamine platinum, and hexaammine platinum hydrochloride. Alternatively, in the case of a dinitrodiammine platinum ammonia solution, platinum is easily dispersed uniformly on the support, and the platinum surface area is likely to increase. When the platinum compound is ethanolamine platinum, platinum is likely to be selectively distributed to the outer shell portion (near the outer surface) of the carrier, and the platinum surface area is likely to increase.

The carrier carrying the platinum compound is baked to decompose the platinum compound, whereby the platinum is carried on the carrier and the dehydrogenation catalyst according to the present embodiment is completed. The firing temperature may be a temperature at which the decomposition of the platinum compound proceeds, for example, about 200 to 500 ° C. In particular, when calcined at 350 ° C. or lower, the aggregation of platinum during calcination hardly occurs, and the platinum surface area in the dehydrogenation catalyst tends to increase.

As described above, when the Group 3 metal is supported on the carrier, it is preferable to perform firing at a high temperature at which the Group 3 metal compound is decomposed. On the other hand, when platinum is supported on a carrier, it is preferable to perform the firing at a low temperature at which platinum aggregation hardly occurs. In order to make these contradictory conditions compatible, in the present embodiment, the Group 3 metal and platinum are not supported on the support at the same time, and both metals are individually supported on the support in the above two steps having different firing temperatures. Thereby, the dehydrogenation catalyst excellent in dehydrogenation activity can be manufactured easily.

(Hydrogen production system and hydrogen production method)
In the present embodiment, hydrogen is produced using the hydrogen production system 100 shown in FIG. The hydrogen production system 100 is a hydrogen production system in a hydrogen station for supplying hydrogen gas as fuel to a fuel cell vehicle, for example.

The hydrogen production system 100 according to this embodiment includes at least a dehydrogenation reactor 2, a first gas-liquid separator 4, a hydrogen purifier 6, and a tank 16. The dehydrogenation reactor 2 includes the dehydrogenation catalyst according to the present embodiment, and hydrogen and organic compounds (aromatic hydrocarbons, etc.) are obtained by dehydrogenation of naphthenic hydrocarbon (organic hydride) using the dehydrogenation catalyst. ) Is generated. That is, the method for producing hydrogen according to the present embodiment includes a step (dehydrogenation step) of generating hydrogen and an organic compound by dehydrogenation of a naphthenic hydrocarbon using the dehydrogenation catalyst according to the present embodiment.

In the dehydrogenation step, naphthenic hydrocarbons are supplied into the dehydrogenation reactor 2. In the dehydrogenation reactor 2, the dehydrogenation catalyst according to the present embodiment is installed. The inside of the dehydrogenation reactor is a reducing atmosphere. When the naphthenic hydrocarbon comes into contact with the dehydrogenation catalyst in the dehydrogenation reactor 2, a dehydrogenation reaction occurs, and at least a pair of hydrogen atoms are extracted from the naphthenic hydrocarbon, and a hydrogen molecule and an organic such as an aromatic hydrocarbon are obtained. A compound is formed. Thus, the dehydrogenation reaction is a gas phase reaction.

The product (hydrogen molecule and organic compound) of the dehydrogenation reaction is supplied from the dehydrogenation reactor 2 into the first gas-liquid separator 4. The temperature in the first gas-liquid separator 4 is not lower than the melting point of the organic compound and lower than the boiling point of the organic compound. The pressure in the first gas-liquid separator 4 is normal pressure (substantially atmospheric pressure). Therefore, the hydrogen molecules in the first gas-liquid separator 4 are gases, and the organic compounds in the first gas-liquid separator 4 are liquids. That is, in the first gas-liquid separator 4, the product of the dehydrogenation reaction is separated into hydrogen gas (gas phase, gas layer) and organic compound liquid (liquid phase, liquid layer). The gas phase (hydrogen-containing gas) in the first gas-liquid separator 4 is supplied to the hydrogen purifier 6. The liquid phase (organic compound liquid) in the first gas-liquid separator 4 is supplied to the tank 16. Note that an organic compound vapor may be mixed in the gas phase. The partial pressure of the organic compound in the gas phase is at most about the saturated vapor pressure of the organic compound. On the other hand, a part of hydrogen generated by dehydrogenation (a trace amount of hydrogen gas) is dissolved in the liquid phase. In addition, organic hydride that has not been dehydrogenated may remain in the liquid phase.

The manufacturing system 100 may further include a second gas-liquid separator. The liquid phase (organic compound liquid) in the first gas-liquid separator 4 may be supplied to the second gas-liquid separator instead of being supplied to the fuel cell vehicle. Below, a 2nd gas-liquid separator is described as the deaeration apparatus 8. FIG. The degassing device 8 may be used to separate the hydrogen gas dissolved in the organic compound liquid from the liquid. The deaeration device 8 may include, for example, a separation membrane that selectively allows only hydrogen gas among hydrogen gas and organic compounds to permeate. Using this separation membrane, hydrogen gas is separated from the organic compound. The separation membrane is, for example, a metal membrane (such as a PbAg-based membrane, a PdCu-based membrane, or an Nb-based membrane), an inorganic membrane (such as a silica membrane, a zeolite membrane, or a carbon membrane), or a polymer membrane (a fluororesin membrane or polyimide). A membrane). In addition, the deaeration apparatus 8 is not limited to an apparatus provided with a separation membrane. The deaeration device 8 may be a device that changes the gas solubility in the liquid by changing the pressure or temperature and performs a method of deaeration.

The hydrogen gas separated from the organic compound by the deaerator 8 is supplied to the low-pressure compressor 12 via the vacuum pump 10 and compressed. The hydrogen gas compressed by the low-pressure compressor 12 is further compressed by the high-pressure compressor 14 and then used as fuel for the fuel cell. On the other hand, the liquid of the organic compound separated from the hydrogen gas by the deaeration device 8 is supplied into the tank 16. The organic compound in the tank 16 may be reused as an organic hydride by being hydrogenated. By the above method, hydrogen gas is separated from the liquid phase (organic compound liquid). However, the hydrogen production system 100 may not include the deaeration device 8, the vacuum pump 10, the low-pressure compressor 12, and the high-pressure compressor 14.

The hydrogen-containing gas supplied from the first gas-liquid separator 4 to the hydrogen purifier 6 is purified in the hydrogen purifier 6. The hydrogen purifier 6 may include, for example, a separation membrane that selectively allows only hydrogen gas among hydrogen gas and organic compounds to permeate. The separation membrane is, for example, a metal membrane (such as a PbAg-based membrane, a PdCu-based membrane, or an Nb-based membrane), an inorganic membrane (such as a silica membrane, a zeolite membrane, or a carbon membrane), or a polymer membrane (a fluororesin membrane or polyimide). A membrane). The hydrogen gas permeates through the separation membrane, thereby increasing the purity of the hydrogen gas. On the other hand, an organic compound (such as unreacted organic hydride) in the hydrogen-containing gas cannot permeate the separation membrane. Therefore, the organic compound is separated from the hydrogen-containing gas, and high-purity hydrogen gas is purified. The purified high-purity hydrogen gas may be used as fuel for the fuel cell without passing through the high-pressure compressor 14, or may be used as fuel for the fuel cell after being compressed by the high-pressure compressor 14. Note that not only an organic compound but also a trace amount of hydrogen gas may not permeate the carbon film. Hydrogen gas that has not permeated the carbon membrane may be recovered together with the organic hydride and supplied as an off-gas into the dehydrogenation reactor 2. Alternatively, the organic compound that has not permeated the carbon film may be collected into the tank 16. The hydrogen purification apparatus 6 is not limited to an apparatus provided with a separation membrane. The hydrogen purifier 6 is selected from the group consisting of, for example, a pressure swing adsorption (PSA) method, a thermal swing adsorption (TSA) method (temperature swing adsorption method), a temperature pressure swing adsorption (TPSA) method, and a cryogenic separation method. An apparatus that performs at least one method may be used. These apparatuses may be used to purify the hydrogen-containing gas, supply the off-gas generated along with the purification into the dehydrogenation reactor 2, and supply the organic compound separated from the hydrogen-containing gas to the tank 16.

Although one aspect of the present invention has been described above, the present invention is not limited to the above-described embodiment.

The effect of the present invention is achieved only by a combination of aluminum oxide, platinum and a Group 3 metal, and is difficult to achieve without aluminum oxide. However, the carrier may contain other components such as silica (SiO ₂ ) or titania (TiO ₂ ) in addition to aluminum oxide as long as the effect of the present invention is not impaired. The effect of the present invention is difficult to achieve without platinum. However, if the amount is small enough not to inhibit the effect of the present invention, other components such as palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), etc. are supported on the carrier in addition to platinum. It may be.

Hereinafter, the content of the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited to the following examples.

(Example 1)
[Group 3 metal loading process]
A molded body made of porous γ-alumina was used as the carrier. The particle size of the molded body was about 1 to 2 mm. An aqueous scandium nitrate solution was supported on 5.18 g of the carrier by a pore filling method. Subsequently, after the support was dried at 100 ° C. overnight, it was fired in air at 550 ° C. for 3 hours to decompose scandium nitrate, thereby supporting scandium on the support.

[Platinum loading process]
A bis (ethanolammonium) hexahydroxoplatinic acid aqueous solution was supported on a support on which scandium was supported by a pore filling method. Subsequently, the support was dried at 100 ° C. overnight and then calcined in air at 330 ° C. for 2 hours to decompose bis (ethanolammonium) hexahydroxoplatinum.

The dehydrogenation catalyst of Example 1 was created through the above steps. The dehydrogenation catalyst of Example 1 includes a support made of γ-alumina, scandium supported on the support, and platinum supported on the support. The amount of scandium supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

(Example 2)
A dehydrogenation catalyst of Example 2 was prepared in the same manner as in Example 1 except that an aqueous solution of yttrium nitrate was used instead of the aqueous solution of scandium nitrate. The dehydrogenation catalyst of Example 2 includes a carrier made of γ-alumina, yttrium supported on the carrier, and platinum supported on the carrier. The amount of yttrium supported on the dehydrogenation catalyst was 0.4% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

(Example 3)
A dehydrogenation catalyst of Example 3 was prepared in the same manner as in Example 1 except that an aqueous solution of lanthanum nitrate was used instead of the aqueous solution of scandium nitrate. The dehydrogenation catalyst of Example 3 includes a support made of γ-alumina, lanthanum supported on the support, and platinum supported on the support. The amount of La supported on the dehydrogenation catalyst was 0.5% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

Example 4
A dehydrogenation catalyst of Example 4 was prepared in the same manner as in Example 1 except that an aqueous solution of cerium nitrate was used instead of the aqueous solution of scandium nitrate. The dehydrogenation catalyst of Example 4 includes a support made of γ-alumina, cerium supported on the support, and platinum supported on the support. The amount of cerium supported in the dehydrogenation catalyst was 0.5% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

(Example 5)
A dehydrogenation catalyst of Example 5 was prepared in the same manner as in Example 4 except that the amount of cerium supported was changed in the Group 3 metal loading step. The dehydrogenation catalyst of Example 5 includes a carrier made of γ-alumina, cerium supported on the carrier, and platinum supported on the carrier. The amount of cerium supported in the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

(Example 6)
A dehydrogenation catalyst of Example 6 was prepared in the same manner as in Example 4 except that the amount of cerium supported was changed in the Group 3 metal loading process. The dehydrogenation catalyst of Example 6 includes a support made of γ-alumina, cerium supported on the support, and platinum supported on the support. The amount of cerium supported on the dehydrogenation catalyst was 1.0% by mass relative to the total mass of the carrier (γ-alumina). The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

(Comparative Example 1)
A dehydrogenation catalyst of Comparative Example 1 was prepared in the same manner as in Example 1 except that the Group 3 metal loading step was not performed. The dehydrogenation catalyst of Comparative Example 1 includes a carrier made of γ-alumina and platinum supported on the carrier. The dehydrogenation catalyst of Comparative Example 1 does not contain a Group 3 metal. The amount of platinum supported on the dehydrogenation catalyst was 0.3% by mass relative to the total mass of the carrier (γ-alumina).

[Evaluation of platinum surface area]
<Example 1>
The platinum surface area contained in the dehydrogenation catalyst of Example 1 was determined using a chemical adsorption method. In the chemical adsorption method, carbon monoxide (CO) was supplied into a container in which the dehydrogenation catalyst of Example 1 was installed. Based on the difference between the volume of CO supplied into the container and the volume of CO discharged outside the container without being adsorbed by the dehydrogenation catalyst in the container, the CO per unit mass of platinum at 40 ° C. The adsorption amount (unit: cm ³ / g) was calculated. Based on the amount of CO adsorbed, the amount of platinum existing on the catalyst surface per unit mass of platinum and acting as an active site, that is, the platinum surface area (unit: m ² / g) was calculated. Table 1 shows the CO adsorption amount and platinum surface area of Example 1.

<Examples 2 to 6, Comparative Example 1>
In the same manner as in Example 1, the CO adsorption amount and platinum surface area of other Examples and Comparative Example 1 were determined. Table 1 shows the CO adsorption amount and platinum surface area of other examples and comparative example 1.

[Evaluation of dehydrogenation activity]
<Example 1>
The dehydrogenation catalyst of Example 1 was charged into a fixed bed flow type reactor. While supplying methylcyclohexane into the reactor, the temperature of the central portion of the catalyst layer was maintained at 330 ° C., and the dehydrogenation reaction of methylcyclohexane was continued in the reactor. The liquid space velocity (LHSV) of methylcyclohexane fed into the reactor was maintained at 11 h- ¹ . When 3 hours had elapsed from the start of the reaction, the gas discharged from the reactor was recovered and cooled to obtain a product oil. The product oil was analyzed with a gas chromatograph-flame ionization detector (GC-FID). From the ratio of the GC area (peak area) of methylcyclohexane contained in the product oil to the GC area of toluene contained in the liquid, methyl The conversion rate (unit: mol%) of cyclohexane was calculated (see the above formula (1)). The conversion rate of methylcyclohexane of Example 1 is shown in Table 1. In addition, “MCH” described in Table 1 means methylcyclohexane.

<Examples 4 to 6, Comparative Example 1>
In the same manner as in Example 1, the conversion rate of methylcyclohexane when the dehydrogenation catalysts of Examples 4 to 6 and Comparative Example 1 were used alone was calculated. Table 1 shows the conversion rates of methylcyclohexane of Examples 4 to 6 and Comparative Example 1. In all cases of Examples 1, 4 to 6 and Comparative Example 1, the volume of the dehydrogenation catalyst installed in the reactor was the same.

In the evaluation of the dehydrogenation activity of Examples 1 and 4 and Comparative Example 1, the conversion rate (unit: mol) of methylcyclohexane at each time point when the elapsed time from the start of the reaction was 2 hours, 3 hours, 4 hours and 5 hours. %) Was calculated. Table 2 shows the conversion ratio of methylcyclohexane at each time point of the dehydrogenation reactions of Examples 1 and 4 and Comparative Example 1.

The platinum surface areas in the dehydrogenation catalysts of Examples 1 to 4 and Comparative Example 1 are shown in FIG. In FIG. 1, “None” corresponds to Comparative Example 1. “Sc” corresponds to Example 1. “Y” corresponds to Example 2. “La” corresponds to Example 3. “Ce” corresponds to Example 4. Table 1 and FIG. 1 show that the platinum surface area is increased by adding a Group 3 metal to γ-alumina supporting platinum.

The conversion rate of methylcyclohexane at each time point of the dehydrogenation reaction of Example 1 and Comparative Example 1 is shown in FIG. In FIG. 2, “No addition” corresponds to Comparative Example 1. “Sc addition” corresponds to Example 1. Table 2 and FIG. 2 show that the dehydrogenation activity is improved by adding scandium to γ-alumina supporting platinum.

The conversion rate of methylcyclohexane at each time point of the dehydrogenation reaction of Example 4 and Comparative Example 1 is shown in FIG. In FIG. 3, “No addition” corresponds to Comparative Example 1. “Ce addition” corresponds to Example 4. Table 2 and FIG. 3 show that dehydrogenation activity is improved by adding cerium to γ-alumina supporting platinum.

The platinum surface areas in the dehydrogenation catalysts of Examples 4 to 6 and Comparative Example 1 are shown in FIG. In FIG. 4, “None” corresponds to Comparative Example 1. “0.3% -Ce” corresponds to Example 5. “0.5% -Ce” corresponds to Example 4. ““ 1.0% -Ce ”corresponds to Example 6. Table 1 and FIG. 4 show that in the range where the amount of cerium added is 0.3 to 1.0%, the surface area of platinum increases with the addition of cerium regardless of the amount of cerium added to the γ-alumina supporting platinum. It is shown that.

(Examples 11 to 15)
A predetermined amount of water, an aqueous solution of cerium nitrate and dilute nitric acid were added to the aluminum hydroxide powder in a pseudo boehmite state and kneaded. The pH of the kneaded product was adjusted to about 3 to 7 by adding dilute nitric acid. Pellets were produced by extrusion molding of the kneaded product. The pellet was dried at 100 to 150 ° C. for 2 hours and then calcined at 550 ° C. for 2 hours to produce a pellet made of γ-alumina supporting C ₂ O ₃ . After the calcined pellet was supported with an aqueous solution of ethanolamine platinum, the pellet was dried. The dried pellets were fired at 330 ° C. for 2 hours.

Through the above steps, dehydrogenation catalysts of Examples 11 to 15 including γ-alumina (support), platinum, and cerium oxide (Ce ₂ O ₃ ) were produced. The amount of platinum supported on the dehydrogenation catalysts of Examples 11 to 15 was adjusted to 0.3% by mass with respect to the total mass of γ-alumina in terms of platinum alone. The amount of Ce ₂ O ₃ supported on the dehydrogenation catalysts of Examples 11 to 15 was adjusted to the values shown in Table 3 below. The supported amount of Ce ₂ O ₃ shown in Table 3 below is a ratio to the total mass of γ-alumina.

In the same manner as in Example 1, the platinum surface area in the dehydrogenation catalysts of Examples 11 to 15 was determined. The platinum surface area of each example is shown in Table 3 below. FIG. 6 shows the relationship between the amount of Ce ₂ O ₃ supported on the dehydrogenation catalysts of Examples 11 to 15 and the platinum surface area.

As shown in Table 3 and FIG. 6, it was confirmed that the platinum surface area was particularly large when the amount of Ce ₂ O ₃ supported was 2.0 to 3.0 mass%.

(Examples 21 to 24)
In the preparation of the dehydrogenation catalysts of Examples 21 to 24, the supported amount of platinum with respect to the total mass of γ-alumina was adjusted to the value shown in Table 4 below, and the supported amount of Ce ₂ O ₃ with respect to the total mass of γ-alumina was adjusted. It adjusted to 2.0 mass%. Except these matters, the dehydrogenation catalysts of Examples 21 to 24 were produced in the same manner as in Examples 11 to 15. Each of the dehydrogenation catalysts of Examples 21 to 24 was provided with γ-alumina (support), platinum, and cerium oxide (Ce ₂ O ₃ ). The platinum dispersion degree in the dehydrogenation catalysts of Examples 21 to 24 was determined based on the following formula 2. The platinum dispersion of each example is shown in Table 4 below.
Dm = V _chem × (SF / 22414) × Mw × (1 / c) × 100 (2)
Dm is a platinum dispersity (unit:%). V _chem is the amount of CO adsorption (unit: cm ³ ) in the dehydrogenation catalyst. SF is the stoichiometric ratio of CO adsorption and is 1. Mw is the atomic weight of platinum (unit: g / mol).

The methylcyclohexane was dehydrogenated using the dehydrogenation catalysts of Examples 21 to 24 at five reaction temperatures of 270 ° C., 280 ° C., 290 ° C., 300 ° C. and 310 ° C. Except for the reaction temperature, the dehydrogenation reaction was carried out using the dehydrogenation catalysts of Examples 21 to 24 in the same manner as in Example 1. Based on the following formula 3, Arrhenius plait (lnk vs. 1 / T) was created.
lnk = ln [SV × 1n {1 / (1-conv.)}]
= InA-E / RT (3)
In is a natural logarithm. k is the rate constant of the dehydration reaction. T is each reaction temperature. conv. Is the conversion of methylcyclohexane in the dehydrogenation reaction at each reaction temperature T. SV is the liquid space velocity of methylcyclohexane fed into the reactor in each dehydrogenation reaction.

Subsequently, the frequency factor A was determined from the intercept of the Arrhenius plot, and the rate constant k ₃₀₀ when the reaction temperature was 300 K was determined from the Arrhenius equation. The speed constant k ₃₀₀ is expressed by the following formula 4.
k ₃₀₀ = A × e ^{−E / RT} (4)

Subsequently, the normalized based on the amount of platinum and Tsuyu amount was determined and the reaction rate r ₃₀₀ at 300 ° C.. The reaction rate r ₃₀₀ is expressed by the following formula 5.
r ₃₀₀ = −k ₃₀₀ × {(1-conv.) / w (Pt)} (5)

The reaction rate r ₃₀₀ of dehydrogenation of methylcyclohexane using each dehydrogenation catalyst, by dividing the reaction rate r ₃₀₀ in the case of using the dehydrogenation catalyst of Example 21, methylcyclohexane using each dehydrogenated catalyst The relative reaction rate of the dehydrogenation reaction was determined. The relative reaction rates when each dehydrogenation catalyst is used are shown in Table 4 below. Table 4 below shows the ratio m ₃ / m _P of the supported amount of platinum (m _P mass%) and the supported amount of Ce ₂ O ₃ (m ₃ mass%) in each dehydrogenation catalyst. FIG. 7 shows the platinum dispersion degree of each dehydrogenation catalyst and the relative reaction rate when each dehydrogenation catalyst is used. The circles in FIG. 7 indicate the degree of platinum dispersion, and the triangles indicate the relative reaction rate.

As shown in Table 4 and FIG. 7, when the supported amount of platinum is about 0.5 to 0.6 mass% (when m ₃ / m _P is (10/3) to 4), platinum is It turns out to function efficiently.

(Examples 31 to 37, Comparative Example 31)
In the preparation of the dehydrogenation catalysts of Examples 31 to 37, the water absorption rate of a commercially available γ-alumina support was measured. Based on this water absorption, an aqueous solution containing a group III metal nitrate shown in Table 5 below at a predetermined concentration was prepared, and the aqueous solution was supported on γ-alumina. Subsequently, the support was dried at 100 ° C. for 8 hours and then calcined at 500 ° C. for 2 hours. An aqueous solution of a platinum compound was supported on the carrier after firing. Subsequently, the support was dried and calcined at 330 ° C. for 2 hours. Through the above steps, dehydrogenation catalysts of Examples 31 to 37 were produced.

The amount of Group 3 metal oxide supported on each dehydrogenation catalyst was adjusted to the values shown in Table 5 below. The amount of platinum supported on each dehydrogenation catalyst was adjusted to the values shown in Table 5 below. The number of moles of Group 3 metal oxide and the number of moles of platinum in each dehydrogenation catalyst were the values shown in Table 5 below. The ratio of the number of moles of Group 3 metal oxide to the number of moles of platinum in each dehydrogenation catalyst (Metal / Pt) was the value shown in Table 5 below.

In the preparation of the dehydrogenation catalyst of Comparative Example 31, the step of supporting an aqueous solution of a Group 3 metal nitrate on γ-alumina was not performed, and only platinum was supported on γ-alumina. The supported amount of platinum in the dehydrogenation catalyst of Comparative Example 31 was adjusted to the values shown in Table 5 below. The number of moles of platinum in the dehydrogenation catalyst of Comparative Example 31 was the value shown in Table 5 below.

Using the same chemical adsorption method as in Example 1, the ratio of the number of moles of CO adsorbed to platinum to the number of moles of platinum in each dehydrogenation catalyst (CO / Pt) was determined. The CO / Pt for each dehydrogenation catalyst is shown in Table 5 below. FIG. 8 shows the relationship between Metal / Pt and CO / Pt in each dehydrogenation catalyst.

It was confirmed that the dehydrogenation catalysts of Examples 31 to 37 having Group 3 metal oxides had higher CO / Pt and a higher platinum specific surface area than Comparative Example 31.

(Examples 41 to 45)
In the preparation of the dehydrogenation catalysts of Examples 41 to 45, a predetermined amount of water, an aqueous solution of cerium nitrate and dilute nitric acid were added to an aluminum hydroxide powder in a pseudo boehmite state, and these were kneaded. The pH of the kneaded product was adjusted to about 3 to 7 by adding dilute nitric acid. Pellets were produced by extrusion molding of the kneaded product. The pellet was dried at 100 to 150 ° C. for 2 hours and then calcined at 550 ° C. for 2 hours to produce a pellet made of γ-alumina supporting C ₂ O ₃ . After carrying | supporting the platinum compound aqueous solution shown in following Table 6 to the pellet after baking, the pellet was dried. The dried pellets were fired at 330 ° C. for 2 hours.

Through the above steps, dehydrogenation catalysts of Examples 41 to 45 including γ-alumina (support), platinum, and cerium oxide (Ce ₂ O ₃ ) were produced. It was confirmed that all of the dehydrogenation catalysts of Examples 41 to 45 were dark brown. The amount of Ce ₂ O ₃ supported on each dehydrogenation catalyst was adjusted to 2% by mass with respect to the total mass of γ-alumina. The concentration of the aqueous solution of each platinum compound used in Examples 41 to 45 was adjusted to the values shown in Table 6 below. The pH of each platinum compound aqueous solution used in Examples 41 to 45 was adjusted to the values shown in Table 6 below. The valence of platinum in each platinum compound used in Examples 41 to 45 was a value shown in Table 6 below. In the same manner as in Example 1, the platinum surface area in the dehydrogenation catalysts of Examples 41 to 45 was determined. The platinum surface area of each dehydrogenation catalyst is shown in Table 6 below.

As shown in Table 6, it was confirmed that the platinum surface areas of Examples 41 to 43 and 45 were larger than those of Example 44.

The hydrogen gas obtained by the dehydrogenation reaction of naphthenic hydrocarbons using the dehydrogenation catalyst according to the present invention is used as fuel for fuel cells, for example.

DESCRIPTION OF SYMBOLS 2 ... Dehydrogenation reactor, 4 ... 1st gas-liquid separator, 6 ... Hydrogen purification apparatus, 8 ... 2nd gas-liquid separator (degassing apparatus), 10 ... Vacuum pump, 12 ... Low pressure compressor, 14 ... High pressure compressor , 16 ... tank, 100 ... hydrogen production system.

Claims

A carrier comprising aluminum oxide, platinum, and a Group 3 metal,
Dehydrogenation catalyst for naphthenic hydrocarbons.
The amount of the Group 3 metal supported is 0.1 to 5.0% by mass with respect to the total mass of the aluminum oxide in terms of the oxide of the Group 3 metal.
The dehydrogenation catalyst according to claim 1.
The amount of platinum supported is m P mass% with respect to the total mass of the aluminum oxide in terms of platinum alone,
When the supported amount of the Group 3 metal is m 3 % by mass with respect to the total mass of the aluminum oxide in terms of the oxide of the Group 3 metal,
m 3 / m P is (10/3) to 4,
The dehydrogenation catalyst according to claim 1 or 2.
Producing a carrier comprising aluminum oxide and carrying a Group 3 metal;
Carrying a platinum compound solution on the carrier and firing the carrier;
Comprising
A method for producing a dehydrogenation catalyst for naphthenic hydrocarbons.
The platinum compound includes an amine or ammonia;
The manufacturing method of the dehydrogenation catalyst of Claim 4.
Pseudoboehmite-state aluminum hydroxide, Group 3 metal nitrate aqueous solution, and nitric acid are kneaded to prepare a kneaded product, pellets are produced by extrusion molding of the kneaded product, and the pellets are fired To produce the carrier,
The method for producing a dehydrogenation catalyst according to claim 4 or 5.
A dehydrogenation reactor comprising the dehydrogenation catalyst according to any one of claims 1 to 3 and generating hydrogen and the like by dehydrogenation of a naphthenic hydrocarbon using the dehydrogenation catalyst,
Hydrogen production system.
Comprising a step of generating hydrogen by dehydrogenation of a naphthenic hydrocarbon using the dehydrogenation catalyst according to any one of claims 1 to 3.
A method for producing hydrogen.